A proposed Lawsonella species with distinct functional features from L. clevelandensis revealed by metagenomics

The skin serves as a vital barrier, largely influenced by the commensal microbiota. Lawsonella clevelandensis, the currently recognized sole species in the genus Lawsonella, has gained increased attention as a cause of abscesses but is often overlooked due to its fastidious nature, which make its isolation and culture in the lab particularly challenging. Here, a comprehensive genomic investigation of Lawsonella was conducted using a cultivation-free metagenomic approach, focusing on 39 newly generated and 12 publicly available genomes. A novel species represented by 43 metagenome-assembled genomes (MAGs) was proposed based on mono-clade formation, 16S rDNA sequence similarity and genome-wide average nucleotide identity (ANI) values. All these MAGs were initially identified as L. clevelandensis A by GTDB-tk. Here, we designed them as 'Candidatus Lawsonella tjsk' sp. nov.. Distinct genomic characteristics between this newly proposed species and L. clevelandensis were observed. Significant fundamental functional differences between the two species were revealed by species-specific genes.